The term ablation electrode in this respect stands for any small area energy coupling-out element and the term neutral electrode stands for any comparatively large-area energy coupling-out element. In addition the term ablation catheter is used to denote any arrangement of small area energy coupling-out elements which are spatially associated with each other by suitable connecting means.
The invention concerns in particular the general problem of producing line-shaped lesions of sufficient depth throughout in order, for example, to achieve an enduring curative effect in the ablation of tachyarrhythmmia phenomena.
To produce linear lesions of that kind it is known, for example, to use an ablation catheter with a relatively elongated electrode at the free end of the catheter. The linear lesion is produced by the electrode being slowly moved in its longitudinal direction while it is connected to an energy source.
Another ablation arrangement is known from international patent application WO-A97/20510. Described therein is an HF-ablation system in which HF-energy can be delivered simultaneously and in a predetermined phase association by way of a plurality of electrodes of a multipolar catheter. In that case, a number of power modules corresponding to the number of electrodes is used. That arrangement is complicated and expensive due to its structure. In addition, the various electrode systems are not decoupled from each other so that measurement or regulating circuits based thereon have a mutual influencing effect.